SOME Vampires can walk around in daylight, but I think it's more likely that Mordheim is just so saturated in Evil that the sun just never comes out.

Or, possibly the most boring explanation... the rulebook alludes to the fact that the the reason Vampires have Dregs at all is so that someone can go shopping during the day. Which leads me to assume that they just come out to kick other warbands asses at night.

From the little reading available on Mordheim, it does look like the comet's dust and general dirt of Mordheim does obscure the sun enough that Vampires can operate normally during even sunlight hours within its walls.

The forests on both sides of the River Stir around Mordheim are also pretty dense, so a Vampire should be alright there - just watch out for any meadows!

Second, if I took a stab at it I'd say that the vampires in Mordheim are young vampires and haven't totally and completely turned to the "darkside" yet. As mentioned earlier, some vampires can roam about in the sun for short periods of time. So I would hazard a guess to say we get to witness the rise of a vampire (insert evil, maniacal laughter here).

Mweaver, that's a good question. In the Felix and Gotrek novels, Adolphus Kreiger couldn't handle the sunlight, but in Genevieve the Vampire, it states she can handle the sunlight and that there are several different vampires with their own peculiarities. I mean, I've never read the books themselves...ahem... I've heard that is how they explain vampires...

Vampires in Warhammer in general can't handle sunlight. But I'm pretty sure that only means DIRECT sunlight, and really powerful ones aren't affected. But all of them, even Genevieve, are considerably weakened during the day.

Warhammer basically says that there are many different kinds of Vampires. In the army book, there are options for buying special abilities like a ghost-form or wings which don't exactly come standard. But for a player character in an RPG, I wouldn't stray too far from the generic vampires. Sunlight is, in my opinion, a very necessary weakness.

In the 2001 Vampire Counts Army Book (the one with the blood lines), in the introduction it says: "The only thing [vampire lords] fear are the rays of the sun that are the bane of their type, searing their unholy flesh and eventually destroying these abominations against nature. This is of no help when the armies of the vampire counts march to war, since the Lords of the Undead can use their necromantic powers to summon billowing storm clouds protecting themselves and their minions from the hated sun". (p. 3).

So this weakness is in the WH version of vampires too, GW just doesn't see the need to make rules about it, and fair enough.

Take a look at some of the flavour pictures in the rule book. Mordheim as it is envisioned in the fluff is a gothic medieval city with towering pillars, massive walls, arches, disturbingly tall half-tudor houses. It's pretty safe to say that the entire city is covered in shade.

During dark, moonless nights, black coaches arrive at the gates of Mordheim carrying coffins. Ghouls scuttle from their hiding places to greet them, and corpses are stirred by a command which the living cannot hear. Following the commands of the Vampire, they hunt for shards of wyrdstone.